PROJECT SUMMARY Background. HIV prevalence among gay, bisexual, and other men who have sex with men (MSM) in China has increased from less than 1.0% in 2003 to 9.2% in 2016. Lack of action will lead to 1 in 6 Chinese MSM being infected with HIV by 2025; the majority will be young (YMSM). Stigma fuels China?s HIV epidemic among YMSM. Chinese YMSM face a lack of equal rights and legal protections, identity concealment is normative, and conversion therapy is widespread. Chinese values of filial piety and norm conformity further strain YMSM. This stigma gives rise to minority stress reactions, including identity concealment, internalized homonegativity, and sensitivity to identity-based rejection. Both minority stress and associated poor mental health compromise YMSM?s HIV prevention through avoidance coping, low self-worth, impulsivity, and unassertiveness. Our team has created the first intervention tested for efficacy with YMSM that addresses these minority stress reactions and related processes. This cognitive-behavioral (CBT) intervention, called ESTEEM, shows strong preliminary efficacy across minority stress, mental health, and HIV risk behavior. Yet, ESTEEM was developed in the US and currently requires in-person delivery of 10 1-hour sessions, precluding widespread implementation in China. Now, advancements in our research allow us to prepare ESTEEM for broad reach. Preliminary Studies. First, we culturally adapted in-person ESTEEM for Chinese YMSM across an 8-stage adaptation process with YMSM and stakeholders (n=56), including a small open pilot with Chinese YMSM (n=8). Second, we worked with our colleagues in Sweden ? world leaders in internet-based CBT (iCBT) ? to create an iCBT version of ESTEEM. iCBT combines a self-guided mobile platform with brief counselor feedback and online exercises and homework, requiring 80% less counselor time than in-person ESTEEM. In a small US pilot (n=10), iCBT ESTEEM was highly functional. We incorporate these advances to develop Chinese ESTEEM iCBT ? a highly efficient, private intervention that addresses minority stress and mental health as HIV prevention. Aims. (1) Transform our recently created Chinese ESTEEM in-person materials (e.g., manual, handouts) into iCBT content (e.g., self-guided exercises, videos) and ensure its comprehension (n=10 YMSM). (2) Test the initial efficacy of Chinese ESTEEM iCBT for reducing at-risk YMSM?s past-90-day HIV-risk behavior, against a weekly self-monitoring control. (3) Identify implementation barriers and facilitators of Chinese ESTEEM iCBT through analysis of Aim 2 data (e.g., counselor fidelity) and qualitative interviews with Aim 2 participants (n=20), counselors (n=4), government stakeholders (e.g., Chinese CDC, medical clinic staff, n=12), and implementing partners (e.g., HIV-prevention NGOs, LGBTQ centers, n=12). In developing a highly efficient platform to disseminate our minority stress-mental health intervention, we also position ourselves for sustained future collaboration, including on research to study the ultimate uptake of this intervention in established settings across China and other low/middle-income countries severely affected by HIV.